Liquid boiler



Feb. 20, 1934. CQULSQN, JR 1,948,369

LIQUID BOILER Origin a1 Filed Aug. 28. 1930 Inventor: Bevis P. Coulson J'r:

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Patented Feb. 20, 1934 UNITED STATES LIQUID cornea Bevis P. Coulson, Jr., Schenectady, N. Y., assignor to General Electric Ccmpany, a corporation of New York Application August 28, 1930. Serial No. 478,399 Renewed December 8, 1932 3 Claims.

The present invention relates to boilers for generating vapor from liquid, and especially to boilers intended for vaporizing a liquid having a high boiling point as compared with water, and which may be comparatively heavy. Such a liquid is mercury, mercury vapor now being utilized for driving elastic fluid turbines and for other purposes, such as a heating agent in connection with industrial processes.

The invention relates particularly to boilers of the type such as that disclosed in the application of W. L. R. Emmet and myself, Ser. No. 306,486, filed September 17, 1928, and has for its general object to provide an improved construction and arrangement in a boiler of this type whereby a more rapid circulation of the liquid to be evaporated is obtained.

For a consideration of what I believe to be novel and my invention attention is directed to the accompanying description and the claims appended thereto.

In the drawing, Fig. l is a view partly in section, of a boiler structure embodying my invention, and Fig. 2 is a detailed sectional view on a larger scale of a single boiler tube.

Referring to the drawing, 1 indicates a boiler drum or casing, and 2 indicates boiler tubes depending from the lower portion thereof. Each boiler tube 2 comprises an outer tube 3 which at its upper end is fixed in an opening in drum 1 and is welded thereto, as indicated at 4, and a core 5 which is located inside tube 3 and provides a central passage 6 through which the liquid to be vaporized flows to the bottom of the tube, and an annular passage 7 through which the liquid flows upward and in which it is vaporized. Core 5 may be formed from an inner tube 8 and an outer tube 9 Welded together at their upper and lower ends as indicated at 10. An upper portion 3a of the outer tube 3 which is inserted in an opening of the casing or drum 1 is neckedin, that is, reduced in its diameter to avoid excessive weakening of the drum by the provision of the openings therein. The tubes are arranged close to each other as shown in Fig. 1, and a drum comprises generally more than a hundred tubes. With the necking-in of the the upper portions of the outer tubes a great many tubes may be provided without causing excessive weakening of the lower portion of the boiler drum wall.

The space between the tubes 8 and S) is filled with air, preferably, which forms a heat insulating medium to prevent transfer of heat to the liquid to be vaporized as it flows downward through core passage 6. The core 5 is held in spaced relation to the tube 3 to define annular passage '7 by means of short longitudinal projections 11 which may be formed by forcing outwardly portions of the wall of core tube 9. At its lower end the core is held in spaced relation with tube 3 by suitable knobs or projections 12 and it is held down in tube 3 by knobs or projections 13 which engage the inwardly extending shoulder 14 at the upper portion of tube 3. Tube 5 3 maybe formed of a plurality of sections welded together, as is indicated at 15, the core 5 being inserted in tube 3 before the upper section is put in place.

Inside drum or casing 1 and located in spaced relation thereto, is a baiile plate 16 provided withopenings 17 through which the liquid to be vaporized is supplied to core passages 6. Baffle plate 16 is held in spaced relation to the adjacent surface of the drum 1 by projections 18 which may be in the form of heads on studs threaded in the bafiie plate. Associated with the boiler structure are filler blocks 19 which serve to occupy space within the drum so as to decrease the volume which is required to be filled with the liquid to be vaporized. 20 indicates lagging for the boiler structure, which lagging may be fixed in place in any suitable manner.

The general structure of the apparatus is more fully illustrated and described in the above referred to application, and is to be talren as representing a specific type of construction to which the following part of my invention may be applied. In connection with a boiler of the type so far described, the liquid to be vaporized is fed through baflie plate passages 17 to core passages 6 and the vapor generated in boiler tubes 2 flows from the annular passages 7 at the top of the outer tube 3.

In connection with the operation of such a boiler, it is important that the flow of liquid through the baffle plate passages to the core passages be continuous and uninterrupted, for should an interruption in the flow to a core passage occur, it'may result in burning out of the tube. For manufacturing reasons, and because of the eifect of heat upon the structure, it is not practicable to form a rigid connection between the upper ends of the cores and the bafile plate openings 1'7.

Specifically, the object of my invention is to provide an improved connection between the bafiie plate passages 17 and the core passages 6 for conveying the liquid to be vaporized from the passages 17 to the passages 6.

According to my invention, I connect each baffle plate passage 17 to its corresponding core passage 6 by means of a tube 21, the tube being rigidly connected at its upper end in the baflle plate passage 1'7 by suitable means such as by being rolled tight or by welding, and extending down to core passage 6 but without having me chanical connection with it, and I provide in connection with the lower end of tube 21, a packing sleeve 22 which may be formed integral with and as a continuation of tube 21. Packing sleeve 22 extends down into core passage 6 in spaced relation to the wall of the core passage to provide an annular sealing or packing space 23, the sleeve extending down into the core passage a distance such that the packing space 23 offers a resistance to flow of vapor from space 7 through it of a value such that under the most extreme conditions met with in operation no flow of vapor can take place from passage 7 to core passage 6, the resistance to flow being due to the hydraulic head of mercury in space 23. The width of space 23 may be small. For example, I have found a width of the order of 0.01 inch satisfactory. If

desired, the space may vary in width, being wider at the lower end than at the top. Also on sleeve 22 is an annular projection or enlargement 24 which has a very close clearance with the inside surface of wall 8, for example a clearance of the order of a few'mils.

By the above described arrangement, it will be seen that I provide a tube for conveying liquid from above baffle plate 16 to a core passage which sleeve does not have a mechanical connection with the core and in conjunction therewith I provide a packing or sealing means in the, form of a relatively long narrow passage which functions to prevent fiow of vapor through the passage betvveen the sleeve and the core. When the boiler is operating, core passage 6 is filled with liquid mercury to a level in the vicinity of its upper end which means that the space 23 is filled with mercury to a level depending upon the difference in pressure between that of the vapor in space 7 at the top of the core and that of the hydraulic head in passage 23 above the lower end of packing sleeve 22. The space 23 may be made of any desired vertical length. Preferably it is made of a vertical length such that the greatest difference in pressure to be met with in operation will not be sufiicient to force vapor down through the space 23 against the hydraulic head of mercury in passage 6. Under certain conditions of light load, it may happen that the pressure of the vapor at the top of passage 7 is less than that due to the hydraulic head of liquid in core passage 6 above the lower end of sleeve 22, in which case there would be a tendency for liquid to fiow up through space 23.

The purpose of enlargement 24 is to limit the flow of liquid under these circumstances to a minimum.

This arrangement has the advantage that since there is no mechanical connection between tube 21 and the core, slight warping of a boiler tube during operation or expansion and contraction does not affect the connection between the tube 21 and the core. Also the connection is not affected if during operation an outer tube 3 expands and pulls its core downward with it.

The arrangement has the further advantage that it is simple in structure and easy to assemble since there are no parts requiring accurate fitting. As will be clear, a tube 21 can be readily positioned even though its core is slightly out of alignment.

The necking-in of the upper portion of the outer tubes, in addition to the above mentioned advantages, also provides a simple solution of the problem of maintaining the velocity of the vapor rising from the vapor space or passage 7, resulting in a rapid circulation of the fluid. An outer tube 3 of uniform diameter would necessitate making the upper portion of tubular member 21 either considerably larger or of stronger walls in order to obtain the same cross section of the vapor space. A greater diameter for the member 21 in turn would mean providing larger holes in the bafile plate. Thus it can readily be seen that the particular shape of the outer tubes has, besides technical advantages, also the advantages of reduced cost of manufacture. The reduced diameter of the upper portion of the outer tube, together with the sealing arrangement between the liquid and Vapor passages, effect in a simple manner a rapid circulation of the liquid to be evaporated.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the appara-tus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

. What I claim as new and desire to secure by Letters Patent of the United States, is:

1 In a boiler structure, the combination of a casing, a boiler tube connected to the casing, said boiler tube being provided with a core having a central passage, a baiiie plate the casing, means providing a conduit for conveying liquid from above the bafiie plate to the core passage, said conduit being not mechanically connected to said core and means providing an axially ex" tending sealing passage for preventing leakage from the space outside the core to the core passage.

2. In a boiler structure, the combination of a casing, a boiler tube connected to the casing, said boiler tube being provided with a core having a central passage, a baiile plate in the casing, means providing a conduit for carrying liquid from above the baiiie plate to the core passage, said conduit being not mechanically con nected to said core and a depending sleeve which defines with the adjacent wall of the core a sealing passage for preventing leakage from the space outside the core to the core passage.

3. In a boiler structure, the combination of a casing, a boiler tube connected to the casing, said boiler tube being provided with a core having a central passage, a bafile plate in the casing, a tube for conveying liquid from above the baffle plate to the core passage, and a sleeve which forms an extension of the tube and projects into the core passage in spaced relation to its Wall to form a sealing space for preventing leakage around the tube into the core passage.

BEVIS P. COULSON, JR. 

